In normal-weight subjects, the effects of a high carbohydrate (hi-CHO) vs. high fat (hi-Fat) diet/meal on lipoprotein lipase (LPL) responsiveness in adipose tissue (AT) or skeletal muscle (SM) will predict weight stability vs. weight gain over 5 years. In obese subjects, the effects of a hi-CHO vs. hi-Fat diet/meal on tissue-specific LPL responsiveness will predict weight stability of the obese weight vs. additional weight gain over 5 years. Some of the variability in LPL responsiveness to insulin and/or diet (meals) between subjects could relate to weight maintenance (less sensitive) or weight gain (more sensitive).